Hinge module and foldable electronic device including the same

ABSTRACT

A hinge module according to one embodiment includes a fixed structure including a central portion, a guide portion having an edge facing an edge of the central portion, and a support portion configured to connect the central portion and the guide portion, wherein an interior space is formed between the central portion and the guide portion, a connecting shaft extending into the interior space through the central portion and including a gear formed on at least a part of an outer circumferential surface of the connecting shaft, and a rotary structure disposed in the interior space, the rotary structure including a circular arc shaped gear having a plurality of gear teeth arranged in a circular arc shape and that are engaged with the gear, wherein the rotary structure rotates about a virtual axis of rotation passing through a center of a circular arc of the circular arc shaped gear.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application is based on and claims priority under 35 U.S.C. § 119to Korean Patent Application No. 10-2019-0019576, filed on Feb. 19,2019, in the Korean Intellectual Property Office, the disclosure ofwhich is incorporated by reference herein its entirety.

BACKGROUND 1. Field

One or more embodiments of the instant disclosure generally relate to ahinge module and a foldable electronic device including the same.

2. Description of Related Art

Certain portable electronic devices may provide a variety of functionsvia a variety of applications. For example, certain types of theportable electronic devices may provide functions such as data and voicecommunication, photo or video capture with a camera, Internetcommunication, multimedia playback and output on a display, etc.Recently, these portable electronic devices may also be used for gaming.

One type of portable electronic devices is a folder type. This typeincludes two housings connected to rotate relative to each other. Thedisplay of the device is disposed on only one of the housings, and theother housing includes the input device, such as a keypad, with whichthe user inputs commands. This folder type electronic device may beunfolded when in use and may be folded to be easily stowed away when notin use. However, the display of this folder type electronic device maybe relatively small because the display is contained in only the onehousing.

In recent years, another type of foldable electronic device has beendeveloped to include a flexible display, which, like the folder type,can be easily folded and stowed away when not in use. But unlike thefolder type, the foldable display may be disposed on both housings,allowing the display to increase in size. The foldable electronic devicemay include a display disposed on two housings connected to rotaterelative to each other. The flexible display may include a partial areathat can be deformed into a curved surface or a flat surface. The twohousings may be unfolded to provide a large screen to the user when thefoldable electronic device is used, and may be folded to provideportability when the foldable electronic device is not used.

The above information is presented as background information only toassist with an understanding of the disclosure. No determination hasbeen made, and no assertion is made, as to whether any of the abovemight be applicable as prior art with regard to the disclosure.

SUMMARY

A hinge module may be used for the foldable electronic device, and mayinclude a fixed structure fixedly coupled to a housing, and rotarystructures that rotate relative to the fixed structure. The rotarystructures may be disposed on opposite sides of the fixed structure withrespect to a connecting shaft. However, when an impact is applied to theelectronic device including the hinge module, for example when theelectronic device is dropped, the rotary structures may be separatedfrom the housing. Furthermore, the hinge module may additionally includea separate elastic member that applies a coupling force to the rotarystructures and the fixed structure in the direction of the connectingshaft. Due to this, the number of components of the hinge module isrelatively large, and therefore the assembly process for the hingemodule may be complicated.

Aspects of the disclosure are to address at least the above-mentionedproblems and/or disadvantages and to provide at least the advantagesdescribed below. Accordingly, an aspect of the disclosure is to providea hinge module including a structure capable of maintaining a couplingof a rotary structure and a fixed structure even when an external impactis applied, and an electronic device including the hinge module.

The problems to be solved by the disclosure are not limited to theaforementioned problems, and any other problems not mentioned hereinwill be clearly understood from the following description by thoseskilled in the art to which the disclosure pertains.

In accordance with an aspect of the disclosure, a hinge module includesa first fixed structure that includes a first central portion, a firstsupport portion extending from the first central portion in a firstdirection, and a first guide portion extending from the first supportportion in a third direction perpendicular to the first direction, asecond fixed structure that includes a second central portion coupled toone side of the first central portion that faces a second directionopposite to the first direction, a second support portion extending fromthe second central portion in the second direction, and a second guideportion extending from the second support portion in a fourth directionperpendicular to the second direction, the second fixed structure beingintegrally or removably coupled to the first fixed structure, a firstconnecting shaft that includes a first gear formed on at least a part ofan outer circumferential surface thereof and extends in the firstdirection and that passes through at least a part of the first centralportion of the first fixed structure such that at least a part of thefirst gear is disposed between the first central portion and the firstguide portion, a first rotary structure that is disposed between thefirst guide portion and the first central portion and that includes afirst circular arc shaped gear engaged with the first gear, the firstrotary structure being coupled with the first connecting shaft so as tobe rotated about a first virtual axis of rotation passing through acenter of a circular arc of the first circular arc shaped gear, a secondconnecting shaft that includes a second gear formed on at least a partof an outer circumferential surface thereof and extends in the seconddirection and that passes through at least a part of the second centralportion of the second fixed structure such that at least a part of thesecond gear is disposed between the second central portion and thesecond guide portion, the first connecting shaft and the secondconnecting shaft being linked with each other so as to be rotated inopposite directions, and a second rotary structure that is disposedbetween the second guide portion and the second central portion and thatincludes a second circular arc shaped gear engaged with the second gear,the second rotary structure being configured to be rotated about asecond virtual axis of rotation passing through a center of a circulararc of the second circular arc shaped gear, by rotation of the secondconnecting shaft.

In accordance with another aspect of the disclosure, a hinge moduleincludes a fixed structure that includes a central portion, a guideportion having an edge facing an edge of the central portion, and asupport portion that connects the central portion and the guide portion,an interior space being formed between the central portion and the guideportion, a connecting shaft extending into the interior space throughthe central portion and including a gear formed on at least a part of anouter circumferential surface of the connecting shaft, and a rotarystructure that is disposed in the interior space and that includes acircular arc shaped gear that includes a plurality of gear teetharranged in a circular arc shape and that are engaged with the gear, inwhich the rotary structure rotates about a virtual axis of rotationpassing through a center of a circular arc of the circular arc shapedgear.

In accordance with another aspect of the disclosure, an electronicdevice includes a housing structure that includes a first housing, asecond housing, and a hinge housing disposed between the first housingand the second housing, a flexible display that is disposed on thehousing structure so as to extend from the first housing to the secondhousing and that includes a first area formed of a flat surface of thefirst housing, a second area formed of a flat surface of the secondhousing, and a folding area formed between the first area and the secondarea and configured to be folded to be flat or curved, and a hingemodule that is disposed in the hinge housing and that rotates the firsthousing about a first virtual axis of rotation extending in a firstdirection and rotates the second housing about a second virtual axis ofrotation parallel to the first virtual axis of rotation. The hingemodule includes a fixed structure that is fixedly disposed in the hingehousing and that includes a central portion, a first support portionextending from the central portion in the first direction, a first guideportion extending from the first support portion in a third directionperpendicular to the first direction, a second support portion extendingfrom the central portion in a second direction opposite to the firstdirection, and a second guide portion extending from the second supportportion in a fourth direction perpendicular to the second direction, afirst rotary structure disposed between the first guide portion and thecentral portion and connected with the first housing, and a secondrotary structure disposed between the second guide portion and thecentral portion and connected with the second housing.

Other aspects, advantages, and salient features of the disclosure willbecome apparent to those skilled in the art from the following detaileddescription, which, taken in conjunction with the annexed drawings,discloses various embodiments of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the disclosure will be more apparent from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is views illustrating a flat state of a foldable electronicdevice according to an embodiment;

FIG. 2 is perspective views illustrating a flat state and a folded stateof the foldable electronic device according to an embodiment;

FIG. 3 is an exploded perspective view of the electronic deviceaccording to an embodiment;

FIG. 4 is a view illustrating the interior of the electronic deviceaccording to an embodiment;

FIG. 5 is a view illustrating the interior of a hinge housing of theelectronic device according to an embodiment;

FIG. 6 is a transparent view of a hinge module according to anembodiment;

FIG. 7 is a sectional view of the hinge module according to anembodiment;

FIG. 8 is a sectional view of the hinge module according to anembodiment;

FIG. 9 is a sectional view illustrating a state in which a first rotarystructure and a second rotary structure of the hinge module according toan embodiment are rotated to an angle of 45 degrees;

FIG. 10 is a sectional view illustrating a state in which the firstrotary structure and the second rotary structure of the hinge moduleaccording to an embodiment are rotated to an angle of 90 degrees;

FIG. 11 is an exploded perspective view of the hinge module according toan embodiment;

FIG. 12 is a perspective view of a fixed structure of the hinge moduleaccording to an embodiment;

FIG. 13 is a perspective view of a rotary structure of the hinge moduleaccording to an embodiment;

FIG. 14 is a view illustrating assembly of a first fixed structure andthe first rotary structure according to an embodiment;

FIG. 15 is a view illustrating a motion of the hinge module according toan embodiment;

FIG. 16 is a view illustrating assembly of the first fixed structure anda first connecting shaft of the hinge module according to an embodiment;

FIG. 17 is a view illustrating assembly of the first fixed structure andsub-gears of the hinge module according to an embodiment;

FIG. 18 is a view illustrating assembly of a second fixed structure, towhich the second rotary structure is assembled, and a second connectingshaft of the hinge module according to an embodiment;

FIG. 19 is a view illustrating insertion-coupling of the first fixedstructure and the second fixed structure of the hinge module accordingto an embodiment;

FIG. 20 is a view illustrating welding of the first fixed structure andthe second fixed structure of the hinge module according to anotherembodiment;

FIG. 21 is a view illustrating assembly of the hinge housing and thefixed structure of the hinge module according to an embodiment;

FIG. 22 is a view illustrating an invariance of the displacement of therotary structure when an external force is axially applied to the hingemodule according to an embodiment;

FIGS. 23A and 23B are perspective views of a hinge module according toan embodiment;

FIG. 24 is a plan view of the hinge module according to an embodiment;and

FIGS. 25A and 25B are views illustrating a rotational motion of thehinge module according to an embodiment.

DETAILED DESCRIPTION

FIG. 1 is views illustrating a flat state of a foldable electronicdevice according to an embodiment. FIG. 2 is perspective viewsillustrating a flat state and a folded state of the foldable electronicdevice according to an embodiment.

As illustrated in FIGS. 1 and 2, the foldable electronic device 1including a flexible display 3 according to an embodiment of thedisclosure may include a first housing 21, a second housing 22, a firstcover 23, a second cover 24, and a hinge housing 25.

Hereinafter, the flat state may refer to the state in which theelectronic device 1 is fully unfolded so that the first housing 21 andthe second housing 22 form an angle of 180 degrees therebetween, and thefolded state may refer to the state in which the electronic device 1 isfully folded so that the first housing 21 and the second housing 22 forman angle of approximately 0 degrees therebetween. In the folded state,at least a portion of the first housing 21 may be in contact with atleast a portion of the second housing 22.

In an embodiment, the first housing 21 and the second housing 22 may beconnected with each other to form the body of the electronic device 1.The first housing 21 and the second housing 22 may be connected so as tobe rotatable relative to each other. When the electronic device 1 is inthe flat state, the front side of the first housing 21 and the frontside of the second housing 22 may form one plane, and when theelectronic device 1 is in the folded state, the front side of the firsthousing 21 and the front side of the second housing 22 may face eachother.

In an embodiment, the first housing 21 and the second housing 22 may bemanufactured by injection molding a synthetic resin, or may be made ofmetals such as stainless steel (STS), aluminum (Al), or titanium (Ti).However, the instant disclosure is not so limited, and the first housing21 and the second housing 22 may be made of various other materials.Thus, parts of the first housing 21 and the second housing 22 may bemade of various metallic or non-metallic materials and may have variousstiffness characteristics to support the flexible display 3.

In an embodiment, part of the flexible display 3 may be disposed on atleast part of the front side of the first housing 21, and the remainingpart of the flexible display 3 may be disposed on at least part of thefront side of the second housing 22. That is, the flexible display 3 maybe formed over at least one side of the first housing 21 and at leastone side of the second housing 22 and is capable of deformation. Thefirst housing 21 and the second housing 22 may have a separate spacetherein in which to accommodate electronic elements, such as a printedcircuit board (e.g., a printed circuit board 6 of FIG. 3) and a battery(not illustrated). These electronic elements are required to drive theflexible display 3. The first cover 23 may be assembled on a rear sideof the first housing 21, and the second cover 24 may be assembled on arear side of the second housing 22. Accordingly, the first cover 23 andthe second cover 24 may prevent the electronic elements from beingexposed to the outside of the device, and prevent infiltration offoreign matter, such as dust or moisture, into the electronic elements,and prevent damage to the electronic elements due to friction or impact.

In an embodiment, the hinge housing 25 may be disposed between the firsthousing 21 and the second housing 22. The hinge housing 25 may cover theoutside of a hinge assembly (e.g., a hinge assembly 4 of FIG. 3) thatconnects the first housing 21 and the second housing 22, and may protectthe hinge assembly. As illustrated in FIG. 2, when the electronic device1 is in the flat state, the hinge housing 25 may be substantiallycovered by the first cover 23 and the second cover 24 so as not to beexposed to the outside. In contrast, when the electronic device 1 is inthe folded state, at least part of the hinge housing 25 may be exposedto the outside from between a lateral portion of the first housing 21and a lateral portion of the second housing 22.

As the electronic device 1 is unfolded to the flat state, the spacebetween the lateral portion of the first housing 21 and the lateralportion of the second housing 22 may become gradually narrower. Further,opposite sides of the hinge housing 25 may be inserted into the firsthousing 21 and the second housing 22. When the electronic device 1 is inthe fully flat state, the hinge housing 25 may be covered by the firstcover 23 and the second cover 24 and may not be exposed to the outside.As the electronic device 1 is folded to the folded state, the spacebetween the lateral portion of the first housing 21 and the lateralportion of the second housing 22 may become gradually wider. Theopposite sides of the hinge housing 25 may be gradually exposed by thefirst housing 21 and the second housing 22. When the electronic device 1is in the fully folded state, at least part of the hinge housing 25 maybe exposed. However, even in this case, the first cover 23 and thesecond cover 24 may cover some remaining portions of the hinge housing25 (e.g. the lateral edges of the hinge housing 25).

In an embodiment, the electronic device 1 may include a waterproofmember (not illustrated) to prevent infiltration of foreign matter, suchas dust or moisture, into the first housing 21 and the second housing22. The waterproof member may be formed between the flexible display 3,and the first housing 21 and the second housing 22 or between the firsthousing 21 and the second housing 22 so that it fills clearances or gapsthat are generated during assembly thereof, thereby sealing the interiorspace of the housings.

In an embodiment, the flexible display 3 may display (output)information processed in the electronic device 1. For example, theflexible display 3 may display execution screen information of anapplication program running in the electronic device 1, which mayinclude a user interface (UI) or a graphic user interface (GUI). Theflexible display 3 according to certain disclosed embodiments of thedisclosure may be deformed by an external force. The deformation may beat least one of curving, bending, folding, twisting, or rolling of theflexible display 3.

In an embodiment, the display area of the flexible display 3 may be aflat surface when no external force is applied to the flexible display3. That is, without deformation, the flexible display 3 may have aninfinite radius of curvature. On the other hand, the display area of theflexible display 3 may be a curved surface when an external force isapplied to the flexible display 3. That is, when deformed, at least partof the flexible display 3 may have a finite radius of curvature.Information may be displayed on the curved surface. Lighting ofsub-pixels arranged in a matrix form may be independently controlled todisplay the visual information. The sub-pixel may be referring to theminimum unit for implementing a color. For example, a pixel may include3 sub-pixels for implementing red, green, and blue.

FIG. 3 is an exploded perspective view of the electronic deviceaccording to an embodiment.

As illustrated in FIG. 3, the electronic device 1 according to anembodiment of the disclosure may further include the hinge assembly 4, ahinge plate 5, and the printed circuit board 6.

In an embodiment, the hinge assembly 4 may couple the first housing 21and the second housing 22 together to allow the first housing 21 and thesecond housing 22 to rotate relative to each other. The first housing 21and the second housing 22 may preferably have shapes of the same sizeand are symmetric to each other with respect to an axis of symmetry F(refer to FIG. 2). Further, the hinge assembly 4 may be connected toadjacent edges of the first housing 21 and the second housing 22. Then,the first housing 21 and the second housing 22 may rotate about thehinge assembly 4.

In an embodiment, the hinge assembly 4 may include a plurality of hingemodules. The hinge modules may include a gear hinge module (e.g., 40 ofFIG. 5) that uses a gear and a gearless hinge module (e.g., 400 of FIG.5) that uses no gear. The gear hinge module 40 may rotate the firsthinge housing 21 and the second housing 22 using the gear. Accordingly,even though a rotational force is applied to only one of the firsthousing 21 and the second housing 22, the other housing maysymmetrically rotate together. That is, the first housing 21 and thesecond housing 22 may rotate in mutual dependence on each other. Incontrast, the gearless hinge module 400 may not include a gear thereinand may include only a rotation guide structure. Accordingly, thegearless hinge module 400 may reduce noise generated by the rotation ofthe housings 21 and 22.

In an embodiment, the printed circuit board 6 may be disposed betweenthe first cover 23 and the first housing 21 or between the second cover24 and the second housing 22. Alternatively, when a plurality of printedcircuit boards 6 are provided, the printed circuit boards 6 may bedisposed between the first cover 23 and the first housing 21 and betweenthe second cover 24 and the second housing 22. Electronic elementsrequired to drive the electronic device 1 may be mounted on the printedcircuit board 6. For example, processor, memory, communication circuit,antenna, microphone, speaker, and/or camera may be mounted on theprinted circuit board 6.

The electronic device 1 according to certain embodiments may furtherinclude a battery (not illustrated). The battery may produce electricpower and may supply the electric power to the inside of the electronicdevice 1. The battery may be disposed between the first cover 23 and thefirst housing 21 or between the second cover 24 and the second housing22.

FIG. 4 is a view illustrating the interior of the electronic deviceaccording to an embodiment.

The hinge housing 25 may be disposed between the first housing 21 andthe second housing 22. Further, as illustrated in FIG. 4, when the firstcover 23 and the second cover 24 are removed, the opposite sides of thehinge housing 25 may be disposed on the first housing 21 and the secondhousing 22, respectively. Accordingly, if the first cover 23 and thesecond cover 24 are assembled, and when the electronic device 1 isunfolded, the opposite sides of the hinge housing 25 may be insertedbetween the first cover 23 and the first housing 21 and between thesecond cover 24 and the second housing 22.

In an embodiment, the first housing 21 and the second housing 22 mayhave the separate space therein. Accordingly, as illustrated in FIG. 4,the electronic elements required to drive the flexible display 3 may bedisposed in the separate space.

FIG. 5 is a view illustrating the interior of the hinge housing of theelectronic device according to an embodiment.

In an embodiment, the hinge housing 25 may cover the outside of thehinge assembly 4 and may protect the hinge assembly 4. Accordingly, asillustrated in FIG. 5, when the hinge housing 25 is removed, the hingeassembly 4 is shown as being disposed between the first housing 21 andthe second housing 22 to connect the first housing 21 and the secondhousing 22.

In an embodiment, the gear hinge module 40 may link the rotationalmotions of the first housing 21 and the second housing 22. The firsthousing 21 and the second housing 22 may be configured to be parallel toeach other about axis F (see FIG. 2), but may rotate about differentaxes of rotation. When the first housing 21 and the second housing 22rotate independently without being linked with each other, slip mayoccur between the first housing 21 and the second housing 22 even whenthe electronic device 1 is folded. Accordingly, the electronic device 1according to an embodiment of the disclosure may include at least onegear hinge module 40.

In an embodiment, to reduce noise generated between gears, theelectronic device 1 may include one gear hinge module 40 and a pluralityof gearless hinge modules 400. For example, as illustrated in FIG. 5,the gear hinge module 40 may be disposed at the center of the hingehousing 25, and the gearless hinge modules 400 may be disposed onopposite sides of the hinge housing 25.

In an embodiment, the hinge assembly (e.g., the hinge assembly 4 of FIG.3) may preferably include a plurality of hinge modules to allow thefirst housing 21 and the second housing 22 to be stably rotated. Thehinge assembly 4 of the electronic device 1 disclosed herein may includevarious hinge modules without being limited to the configurationillustrated in FIG. 5. Hereinafter in the examples below, the hingemodule disclosed herein may include the gear hinge module 40.

FIG. 6 is a transparent view of the hinge module according to anembodiment.

In the illustrated embodiment, the hinge module 40 may include a fixedstructure 41, a first connecting shaft 431 and a second connecting shaft432 that pass through portions of the fixed structure 41, and a firstrotary structure 421 and a second rotary structure 422 that are coupledto the fixed structure 41.

In the illustrated embodiment, the fixed structure 41 may includecentral portions 411 a and 412 a, a first support portion 411 bextending from the central portion 411 a in a first direction, a secondsupport portion 412 b extending from the central portion 412 a in asecond direction opposite to the first direction, a first guide portion411 c extending from the first support portion 411 b in a thirddirection perpendicular to the first direction, and a second guideportion 412 c extending from the second support portion 412 b in afourth direction opposite to the third direction.

In the illustrated embodiment, the first guide portion 411 c may have anedge facing an edge of the central portion 411 a. This creates a spaceto accommodate first rotary structure 421 which may be disposed betweenthe first guide portion 411 c and the central portion 411 a. The firstsupport portion 411 b, together with the first guide portion 411 c andthe central portion 411 a, may surround at least part of the firstrotary structure 421.

In the illustrated embodiment, the second guide portion 412 c may havean edge facing an edge of the central portion 412 a. This creates aspace to accommodate second rotary structure 422 which may be disposedbetween the second guide portion 412 c and the central portion 412 a.The second support portion 412 b, together with the second guide portion412 c and the central portion 412 a, may surround at least part of thesecond rotary structure 422.

In the illustrated embodiment, the fixed structure 41 may include afirst fixed structure 411 that includes the central portion 411 a, thefirst guide portion 411 c, and the first support portion 411 b. Thefixed structure 41 also may include a second fixed structure 412 thatincludes the central portion 412 a, the second guide portion 412 c, andthe second support portion 412 b.

In the illustrated embodiment, the central portions 411 a and 412 a mayinclude sub-gears 44 configured to link a first gear 4341 included inthe first connecting shaft 431 and a second gear 4342 included in thesecond connecting shaft 432. The sub-gears 44 may be disposed betweenthe first fixed structure 411 and the second fixed structure 412. Aneven number of sub-gears 44 may be provided to allow the firstconnecting shaft 431 and the second connecting shaft 432 to rotate inopposite directions.

In the illustrated embodiment, at least part of the first connectingshaft 431 may be disposed to overlap the central portion 412 a of thefixed structure 41. The first connecting shaft 431 may pass through thecentral portion 411 a of the fixed structure 41 such that the remainingpart of the first connecting shaft 431 extends between the first guideportion 411 c and the central portion 411 a. The first connecting shaft431 may have the first gear 4341 formed on at least part of the outercircumferential surface thereof. The first connecting shaft 431 may passthrough the central portion 411 a such that at least a portion of thefirst gear 4341 is located between the first guide portion 411 c and thecentral portion 411 a. The portion of the first gear 4341 between thefirst guide portion 411 c and the central portion 411 a may be engagedwith a first internal gear 4241 of the first rotary structure 421disposed in the space between the first guide portion 411 c and thecentral portion 411 a.

In the illustrated embodiment, at least part of the second connectingshaft 432 may be disposed to overlap the central portion 411 a of thefixed structure 41. The second connecting shaft 432 may pass through thecentral portion 412 a of the fixed structure 41 such that the remainingpart of the second connecting shaft 432 extends between the second guideportion 412 c and the central portion 412 a. The second connecting shaft432 may have the second gear 4342 formed on at least part of the outercircumferential surface thereof. The second connecting shaft 432 maypass through the central portion 412 a such that at least a portion ofthe second gear 4342 is located between the second guide portion 412 cand the central portion 412 a. The portion of the second gear 4342between the second guide portion 412 c and the central portion 412 a maybe engaged with a second internal gear 4242 of the second rotarystructure 422 disposed in the space between the second guide portion 412c and the central portion 412 a.

In the illustrated embodiment, the first rotary structure 421 may bedisposed between the central portion 411 a of the fixed structure 41 andthe first guide portion 411 c. The first rotary structure 421 may makecontact with the first guide portion 411 c of the fixed structure 41 inthe first direction. The first rotary structure 421 may make contactwith the central portion 411 a of the fixed structure 41 in the seconddirection. The first rotary structure 421 may make contact with thefirst support portion 411 b of the fixed structure 41 in the fourthdirection. The displacement of the first rotary structure 421 may befixed in the directions of the connecting shafts (the first connectingshaft 431 and the second connecting shaft 432) because the first rotarystructure 421 is disposed between the central portion 411 a and thefirst guide portion 411 c.

In the illustrated embodiment, the first rotary structure 421 mayinclude the first internal gear 4241. The first internal gear 4241 maybe engaged with the first gear 4341 of the first connecting shaft 431.The first internal gear 4241 may be, for example, a gear formed alongthe inner circumferential surface of an opening formed in the firstrotary structure 421. In an embodiment, the first internal gear 4241 maybe a circular arc shaped internal gear that includes a plurality of gearteeth arranged in a circular arc shape along the inner circumferentialsurface of the opening. The central axis of the circular arc may beperpendicular to the third direction and the fourth direction and may bedisposed at a position spaced apart from the rotating axis of the firstconnecting shaft 431.

In the illustrated embodiment, the second rotary structure 422 may bedisposed between the central portion 412 a of the fixed structure 41 andthe second guide portion 412 c. The second rotary structure 422 may makecontact with the second guide portion 412 c of the fixed structure 41 inthe second direction. The second rotary structure 422 may make contactwith the central portion 412 a of the fixed structure 41 in the firstdirection. The second rotary structure 422 may make contact with thesecond support portion 412 b of the fixed structure 41 in the thirddirection. The displacement of the second rotary structure 422 may befixed in the directions of the connecting shafts (the first connectingshaft 431 and the second connecting shaft 432) because the second rotarystructure 422 is disposed between the central portion 412 a and thesecond guide portion 412 c.

In the illustrated embodiment, the second rotary structure 422 mayinclude the second internal gear 4242. The second internal gear 4242 maybe engaged with the second gear 4342 of the second connecting shaft 432.The second internal gear 4242 may be, for example, a gear formed alongthe inner circumferential surface of an opening formed in the secondrotary structure 422. In an embodiment, the second internal gear 4242may be a circular arc shaped internal gear that includes a plurality ofgear teeth arranged in a circular arc shape along the innercircumferential surface of the opening. The central axis of the circulararc may be perpendicular to the third direction and the fourth directionand may be disposed at a position spaced apart from the rotating axis ofthe second connecting shaft 432.

Hereinafter, the hinge motion of the hinge module illustrated in FIG. 6will be described with reference to FIGS. 7 to 10.

FIG. 7 is a sectional view of the hinge module according to anembodiment. FIG. 7 is a sectional view taken along line A-A′ of FIG. 6.

Referring to FIG. 7, the rotary structures 421 and 422 may include anopening 426 formed therein in a substantially circular arc shape and aninternal gear 424 formed on the inner wall of the opening 426. Theinternal gear 424 (e.g., the first internal gear 4241 or the secondinternal gear 4242 of FIG. 6) may include a plurality of gear teethformed on a substantially circular arc surface. The internal gear 424may be engaged with a gear 434 (e.g., the first gear 4341 or the secondgear 4342 of FIG. 7) that is formed on a connecting shaft 43 (e.g., thefirst connecting shaft 431 or the second connecting shaft 432 of FIG.6). Rotation of the internal gear 424 may be linked with rotation of theconnecting shaft 43. The gear 434 may rotate in a state in which theposition thereof is fixed by the connecting shaft 43 disposed in athrough-hole, and the rotary structures 421 and 422 may rotate about afirst virtual axis of rotation H1 and a second virtual axis of rotationH2, respectively. The first virtual axis of rotation H1 may be an axispassing through the center of the opening 426 of the first rotarystructure 421, where the opening 426 has a circular arc shape. Thesecond virtual axis of rotation H2 may be an axis passing through thecenter of the opening 426 of the second rotary structure 422 andsimilarly has a circular arc shape.

In an embodiment, the first rotary structure 421 may be rotated aboutthe first virtual axis of rotation H1. The first rotary structure 421may include a first surface 4271 facing the flexible display (e.g., theflexible display 3 of FIG. 2) in the flat state and a second surface4272 which is curved and spaced apart from the first virtual axis ofrotation H1 by a predetermined distance in the radial direction. Forexample, the first rotary structure 421 may be substantiallysemicircular.

In the illustrated embodiment, the first rotary structure 421 may rotatesuch that the second surface 4272 follows a first path P1 spaced apartfrom the first virtual axis of rotation H1 at a predetermined interval.In other words, the first path P1 represented by a dotted line in thedrawing may be the path of the second surface 4272 of the first rotarystructure 421 that rotates about the first virtual axis of rotation H1.

In an embodiment, the internal gear 424 (e.g., the second internal gear4242 of FIG. 6) that is included in the second rotary structure 422 maybe engaged with the gear 434 (e.g., the second gear 4342 of FIG. 6) ofthe connecting shaft 43 (e.g., the second connecting shaft 432 of FIG.6), and the second rotary structure 422 may be rotated like the firstrotary structure 421. However, the rotational direction of the secondrotary structure 422 may be opposite to the rotational direction of thefirst rotary structure 421. The second rotary structure 422 may berotated about the second virtual axis of rotation H2. The second rotarystructure 422 may include a first surface 4273 facing the flexibledisplay (e.g., the flexible display 3 of FIG. 2) and a second surface4274 that is curved surface and spaced apart from the second virtualaxis of rotation H2 by a predetermined distance in the radial direction.For example, the second rotary structure 422 may also be substantiallysemicircular.

In the illustrated embodiment, the second rotary structure 422 mayrotate such that the second surface 4274 follows a second path P2 spacedapart from the second virtual axis of rotation H2 at a predeterminedinterval. That is, the second path P2 represented by a dotted line inthe drawing may be the path of the second surface 4274 of the secondrotary structure 422 that rotates about the second virtual axis ofrotation H2.

FIG. 8 is a sectional view of the hinge module according to anembodiment. FIG. 8 is a sectional view taken along line B-B′ of FIG. 6.

Referring to FIG. 8, the hinge module 40 may include a plurality ofgears. The plurality of gears may include a first internal gear 4241,the first gear 4341 engaged with the first internal gear 4241, a firstsub-gear 441 engaged with the first gear 4341, a second sub-gear 442engaged with the first sub-gear 441, the second gear 4342 engaged withthe second sub-gear 442, and the second internal gear 4242 engaged withthe second gear 4342. The first connecting shaft 431 and the secondconnecting shaft 432 may be connected via the sub-gears 44 disposedbetween the first gear 4341 and the second gear 4342. The first sub-gear441 may be engaged with the first gear 4341 and the second sub-gear 442.The second sub-gear 442 may be engaged with the first sub-gear 441 andthe second gear 4342. An even number of sub-gears 44 may be provided torotate the first rotary structure 421 and the second rotary structure422 in opposite directions. For example, when the second rotarystructure 422 and the second internal gear 4242 rotates in a firstrotational direction (the clockwise direction, when the electronicdevice 1 is folded into the folded state), the second connecting shaft432 may rotate in a second rotational direction (the counterclockwisedirection), the second sub-gear 442 may rotate in the first rotationaldirection (the clockwise direction), the first sub-gear 441 may rotatein the second rotational direction (the counterclockwise direction), thefirst connecting shaft 431 may rotate in the first rotational direction(the clockwise direction), and the first internal gear 4241 and thefirst rotary structure 421 may rotate in the second rotational direction(the counterclockwise direction). Accordingly, the first rotarystructure 421 and the second rotary structure 422 may rotate in theopposite directions.

FIG. 9 is a sectional view illustrating a state in which the firstrotary structure and the second rotary structure of the hinge moduleaccording to an embodiment are rotated to an angle of 45 degrees. FIG. 9is a sectional view taken along line A-A′ of FIG. 6. FIG. 10 is asectional view illustrating a state in which the first rotary structureand the second rotary structure of the hinge module according to anembodiment are rotated to an angle of 90 degrees. FIG. 10 is a sectionalview taken along line A-A′ of FIG. 6.

Referring to FIG. 9, the internal gear 424 may be engaged with the firstgear 4341 of the first connecting shaft 431, and therefore the firstrotary structure 421 may be linked with the first connecting shaft 431to rotate in the opposite direction to the rotational direction of thefirst connecting shaft 431. As illustrated in FIG. 8, the second rotarystructure 422 may rotate in the opposite direction to the rotationaldirection of the first rotary structure 421.

Referring to FIG. 9, the first rotary structure 421 may rotate along thepath P1 in the counterclockwise direction, and the second rotarystructure 422 may rotate along the path P2 in the clockwise direction.At this time, the first connecting shaft 431 including the first gear4341 engaged with the internal gear 424 of the first rotary structure421 may rotate in the clockwise direction, and the second connectingshaft 432 including the second gear 4342 engaged with the internal gear424 of the second rotary structure 422 may rotate in thecounterclockwise direction.

Referring to FIG. 10, the first internal gear 4241 may be between thefirst connecting shaft 431 and the first virtual axis of rotation H1.The first internal gear 4241 may be formed on the inner circumferentialsurface of the opening 426 that has a circular arc shape. And in theconfiguration shown in FIG. 10, the first internal gear 4241 may beformed the surface of the opening 426 that is adjacent to the firstvirtual axis of rotation H1. The second internal gear 4242 may bebetween the second connecting shaft 432 and the second virtual axis ofrotation H2. The second internal gear 4242 may be formed on the innercircumferential surface of the opening 426 that has a circular arcshape. And in the configuration shown in FIG. 10, the first internalgear 4241 may be formed the surface of the opening 426 that is adjacentto the second virtual axis of rotation H2.

Referring to FIG. 10, the flexible display 3 may include metal layers 31and 32 that face the first surface 4271 of the first rotary structure421 and the first surface 4273 of the second rotary structure 422. Themetal layers 31 and 32 may be attached to the rear surface of theflexible display 3 to improve the surface quality of the flexibledisplay 3. The metal layers 31 and 32 may not be attached to a foldingarea of the flexible display 3 (e.g., the area illustrated as the curvedsurface of the flexible display in the drawing).

Accordingly, in the state in which the first rotary structure 421 andthe second rotary structure 422 are rotated, unattached areas 311 and312 may extend toward the interior of a recess 418 that is formed in thefixed structure 41 adjacent to the folding area of the flexible display3 (e.g., the area illustrated as the curved surface in the drawing). Theunattached areas 311 and 312 may be at least partially received in therecess 418. The recess 418 of the fixed structure 41 may be have a depthsufficient to receive the unattached areas 311 and 321. Accordingly,metal layers 31 and 32 may be wider than the flat areas of the flexibledisplay 3, thereby improving the surface quality of the flexible display3.

FIG. 11 is an exploded perspective view of the hinge module according toan embodiment.

Referring to FIG. 11, the hinge module 40 may include the first fixedstructure 411, the second fixed structure 412 coupled to one side of thefirst structure 411 that faces the second direction, the first rotarystructure 421 coupled to the first fixed structure 411, the secondrotary structure 422 coupled to the second fixed structure 412, thefirst connecting shaft 431 and the second connecting shaft 432 that passthrough at least part of the first fixed structure 411 and at least partof the second fixed structure 412, respectively, and the sub-gears 44disposed between the first fixed structure 411 and the second fixedstructure 412.

In the illustrated embodiment, the first fixed structure 411 may includethe first central portion 411 a, the first support portion 411 bextending from the first central portion 411 a in the first direction,and the first guide portion 411 c extending from the first supportportion 411 b in the third direction perpendicular to the firstdirection.

In the illustrated embodiment, an edge of the first guide portion 411 cmay face an edge of the first central portion 411 a. The first rotarystructure 421 may be disposed between the first guide portion 411 c andthe first central portion 411 a. The first support portion 411 b,together with the first guide portion 411 c and the first centralportion 411 a, may surround the first rotary structure 421.

In the illustrated embodiment, the second fixed structure 412 mayinclude the second central portion 412 a, the second support portion 412b extending from the second central portion 412 a in the seconddirection, and the second guide portion 412 c extending from the secondsupport portion 412 b in the fourth direction perpendicular to thesecond direction.

In the illustrated embodiment, an edge of the second guide portion 412 cmay face an edge of the second central portion 412 a. The second rotarystructure 422 may be disposed between the second guide portion 412 c andthe second central portion 412 a. The second support portion 412 b,together with the second guide portion 412 c and the second centralportion 412 a, may surround the second rotary structure 422.

In the illustrated embodiment, the first central portion 411 a of thefirst fixed structure 411 may include a first coupling protrusion 4111protruding from the first central portion 411 a in the second direction.The second central portion 412 a of the second fixed structure 412 mayinclude a second coupling protrusion 4121 protruding from the secondcentral portion 412 a in the first direction. The first fixed structure411 and the second fixed structure 412 may be coupled by inserting thefirst coupling protrusion 4111 into a depression formed on the secondfixed structure 412 and inserting the second coupling protrusion 4121into a depression formed on the first fixed structure 411. The sub-gears44 may be disposed between the first fixed structure 411 and the secondfixed structure 412. In some embodiments, the first fixed structure 411and the second fixed structure 412 may be coupled by welding.

In the illustrated embodiment, the first connecting shaft 431 may be atleast partially disposed in the first fixed structure 411 and the secondfixed structure 412. The first connecting shaft 431 may pass through atleast part of the first fixed structure 411 and at least part of thesecond fixed structure 412.

In the illustrated embodiment, the second connecting shaft 432 may be atleast partially disposed in the first fixed structure 411 and the secondfixed structure 412. The second connecting shaft 432 may pass through atleast part of the first fixed structure 411 and at least part of thesecond fixed structure 412.

In the illustrated embodiment, the first connecting shaft 431 and thesecond connecting shaft 432 may include the first gear 4341 and thesecond gear 4342 formed on the outer circumferential surfaces thereof,respectively. The sub-gears 44 may be disposed between the first gear4341 and the second gear 4342. An even number of sub-gears 44 may beprovided to allow the first gear 4341 and the second gear 4342 to rotatein opposite directions. The first sub-gear 441 may be engaged with thefirst gear 4341 and the second sub-gear 4342, and the second sub-gear442 may be engaged with the second gear 4342 and the first sub-gear 441.The sub-gears 44 may be disposed between the first fixed structure 411and the second fixed structure 412.

In the illustrated embodiment, the central portions 411 a and 412 a mayinclude the sub-gears 44 configured to link the first gear 4341 includedin the first connecting shaft 431 and the second gear 4342 included inthe second connecting shaft 432. The sub-gears 44 may be disposedbetween the first fixed structure 411 and the second fixed structure412.

In the illustrated embodiment, the first rotary structure 421 may bedisposed between the first central portion 411 a and the first guideportion 411 c of the first fixed structure 411 so as to make contactwith the first support portion 411 b. The first rotary structure 421 mayinclude a first fastening rod 4251 by which the first rotary structure421 is fastened to a first housing (e.g., the first housing 21 of FIG.3). The first fastening rod 4251 may protrude in the directionperpendicular to the first direction and the third direction.

In the illustrated embodiment, the second rotary structure 422 may bedisposed between the second central portion 412 a and the second guideportion 412 c of the second fixed structure 412 so as to make contactwith the second support portion 412 b. The second rotary structure 422may include a second fastening rod 4252 by which the second rotarystructure 422 is fastened to a second housing (e.g., the second housing22 of FIG. 3). The second fastening rod 4252 may protrude in thedirection perpendicular to the first direction and the third direction.

FIG. 12 is a perspective view of a fixed structure of the hinge moduleaccording to an embodiment. FIG. 13 is a perspective view of a rotarystructure of the hinge module according to an embodiment.

In the illustrated embodiment, the fixed structure 41 (e.g., the firstfixed structure 411 or the second fixed structure 412 of FIG. 11) mayinclude a central portion 41 a (e.g., 411 a or 412 a of FIG. 11), aguide portion 41 c (e.g., 411 c or 412 c of FIG. 11) an edge of which isfacing the central portion 41 a, and a support portion 41 b (e.g., 411 bor 412 b of FIG. 11) that connects the central portion 41 a and theguide portion 41 c. The guide portion 41 c, the central portion 41 a,and the support portion 41 b may form a space 415 therebetween. Asdescribed above, a rotary structure 42 may be disposed in the space 415.

In the illustrated embodiment, the fixed structure 41 may include aguide structure 414 for guiding the rotary structure 42 disposed in thespace 415. The guide structure 414 may protrude toward the rotarystructure 42 disposed in the space 415. The central portion 41 a mayinclude a first guide structure 4141 protruding toward the rotarystructure 42. At least part of the first guide structure 4141 may bereceived in a first guide rail 4231 of the rotary structure 42.

In the illustrated embodiment, the support portion 41 b may include aguide surface 4143 for supporting rotation of the rotary structure 42.The guide surface 4143 may include a circular arc surface having acurvature corresponding to the curvature of rotation of the rotarystructure 42.

In the illustrated embodiment, the guide portion 41 c may include asecond guide structure 4142 protruding toward the rotary structure 42.At least part of the second guide structure 4142 may be received in asecond guide rail 4232 of the rotary structure 42.

In the illustrated embodiment, each of the first guide structure 4141and the second guide structure 4142 may include a first area 414 ahaving a first radius of curvature with respect to a virtual axis ofrotation (e.g., H1 or H2 of FIG. 7) and a second area 414 b having asecond radius of curvature from the virtual axis of rotation.

In the illustrated embodiment, the central portion 41 a may include afirst insertion hole 4171 into which at least part of a first connectingshaft (e.g., the first connecting shaft 431 of FIG. 11) is inserted, asecond insertion hole 4172 into which at least part of a secondconnecting shaft (e.g., the second connecting shaft 432 of FIG. 11) isinserted, a third insertion hole 4173 into which at least part of afirst sub-gear (e.g., the first sub-gear 441 of FIG. 11) is inserted,and a fourth insertion hole 4174 into which at least part of a secondsub-gear (e.g., the second sub-gear 442 of FIG. 11) is inserted.

Referring to FIG. 13, the rotary structure 42 may include the firstguide rail 4231 in which at least part of the first guide structure 4141is received and the second guide rail 4232 in which at least part of thesecond guide structure 4142 is received.

In the illustrated embodiment, the first guide rail 4231 and the secondguide rail 4232 may include first corresponding areas 423 a and secondcorresponding areas 423 b, respectively. The first corresponding areas423 a may make contact with the first areas 414 a of the first guidestructure 4141, and the second corresponding areas 423 b may makecontact with the second areas 414 b of the second guide structure 4142.The first corresponding areas 423 a and the second corresponding areas423 b may include circular arc surfaces having curvatures correspondingto radii of curvature of the first areas 414 a and the second areas 414b, respectively.

In the illustrated embodiment, the second corresponding areas 423 b ofthe guide rails 4231 and 4232 may be larger than the second areas 414 b.For example, the central angles of the circular arc surfaces of thesecond areas 414 b may be smaller than the central angles of thecircular arc surfaces of the second corresponding areas 423 b. This maybe because the first guide structure 4141 and the second guide structure4142 do not extend into the recess 418 formed on the fixed structure 41.That is, when the fixed structure 41 is viewed from above, the secondareas 414 b of the first guide structure 4141 and the second guidestructure 4142 may not overlap the internal space of the recess 418.This is because in the case where part of the first guide structure 4141and part of the second guide structure 4142 are formed in the recess418, the rotation paths of the metal layers 31 and 32 of the flexibledisplay (e.g., the flexible display 3 of FIG. 10), as described above,may collide with the first guide structure 4141 and the second guidestructure 4142.

In the illustrated embodiment, the rotary structure 42 may include thefirst guide rail 4231 and the second guide rail 4232 that are indifferent shapes. For example, the second guide rail 4232 may have alarger depth than the first guide rail 4231 in the direction of thevirtual axis of rotation (e.g., H1 or H2 of FIG. 7). This is designed soas to prevent the direction of the rotary structure 42 from beingchanged when assembling the rotary structure 42 to the fixed structure41. Referring to FIG. 13, the rotary structure 42 may be disposed suchthat the portion on which the fastening rod 425 is formed is locatedaway from the support portion 41 b. To guide the correct assemblydirection of the rotary structure 42, the first guide structure 4141 ofthe fixed structure 41 may protrude toward the rotary structure 42further than the second guide structure 4142, and correspondingly, thefirst guide rail 4231 may have a larger depth than the second guide rail4232.

FIG. 14 is a view illustrating assembly of the first fixed structure andthe first rotary structure according to an embodiment.

In the illustrated embodiment, the first rotary structure 421 may berotated such that the first guide structure 4141 of the first fixedstructure 411 is inserted into one end portion of the first guide rail4231. At this time, the first rotary structure 421 may be rotated aboutthe virtual axis of rotation (e.g., H1 of FIG. 7). The first space 4151is adapted to receive the first rotary structure 421. Accordingly, thefirst rotary structure 421 may be easily inserted into the first space4151.

According to an embodiment, the second guide structure 4142 of the firstfixed structure 411 may be formed on the first guide portion 411 c, andthe first guide structure 4141 of the first fixed structure 411 may beformed on the first central portion 411 a. The first guide rail 4231 andthe second guide rail 4232 may be concavely formed on opposite sides ofthe first rotary structure 421. Accordingly, end portions of the guidestructures 4141 and 4142 may be inserted into the inlets of the guiderails 4231 and 4232.

Referring to FIG. 14, the first rotary structure 421 may be insertedinto the first space 4151 by sliding along the guide surface 4143 in thestate in which the guide structures 4141 and 4142 are received in theguide rails 4231 and 4232. The sliding motion of the first rotarystructure 421 may include rotation of the first rotary structure 421about the virtual axis of rotation (e.g., H1 of FIG. 7).

FIG. 15 is a view illustrating a motion of the hinge module according toan embodiment.

The hinge module 40 may include the fixed structure 41 and the rotarystructures 421 and 422. The first rotary structure 421 may be surroundedby the first central portion 411 a, the first guide portion 411 c, andthe first support portion 411 b. The second rotary structure 422 may besurrounded by the second central portion 412 a, the second guide portion412 c, and the second support portion 412 b. The first connecting shaft431 may pass through at least part of the first central portion 411 a,at least part of the second central portion 412 a, and the first rotarystructure 421, and the second connecting shaft 432 may pass through atleast part of the first central portion 411 a, at least part of thesecond central portion 412 a, and the second rotary structure 422. Aneven number of sub-gears 441 and 442 may be provided between the firstconnecting shaft 431 and the second connecting shaft 432. Accordingly,the first rotary structure 421 and the second rotary structure 422 mayrotate in opposite directions.

For example, when the first rotary structure 421 rotates in a firstrotational direction (the counterclockwise direction), the firstconnecting shaft 431 may rotate in a second rotational direction (theclockwise direction), the first sub-gear 441 may rotate in the firstrotational direction (the counterclockwise direction), the secondsub-gear 442 may rotate in the second rotational direction (theclockwise direction), the second connecting shaft 432 may rotate in thefirst rotational direction (the counterclockwise direction), and thesecond rotary structure 422 may rotate in the second rotationaldirection (the clockwise direction).

FIG. 16 is a view illustrating assembly of the first fixed structure andthe first connecting shaft of the hinge module according to anembodiment. FIG. 17 is a view illustrating assembly of the first fixedstructure and the sub-gears of the hinge module according to anembodiment. FIG. 18 is a view illustrating assembly of the second fixedstructure, to which the second rotary structure is assembled, and thesecond connecting shaft of the hinge module according to an embodiment.FIG. 19 is a view illustrating insertion-coupling of the first fixedstructure and the second fixed structure of the hinge module accordingto an embodiment.

Referring to FIG. 16, the first fixed structure 411 may have the firstinsertion hole 4171 into which the first connecting shaft 431 isinserted. The first connecting shaft 431 may be inserted into the firstinsertion hole 4171. At this time, a portion of the first connectingshaft 431 on which the first gear 4341 is formed may not be insertedinto the first fixed structure 411. FIG. 19 is a view illustratingassembly of the first fixed structure 411 and the second fixed structure412 of the hinge module according to an embodiment.

Referring to FIG. 17, the first fixed structure 411 may have theinsertion holes 4173 and 4174 into which the sub-gears 441 and 442 areinserted. After the assembly of the first connecting shaft 431, thefirst sub-gear 441 may be inserted into the third insertion hole 4173formed in the first fixed structure 411, and the second sub-gear 442 maybe inserted into the fourth insertion hole 4174. The first sub-gear 441and the second sub-gear 442 may be inserted into the third insertionhole 4173 and the fourth insertion hole 4174, respectively, such thatthe first sub-gear 441 is engaged with the first gear 4341 of the firstconnecting shaft 431 and the first sub-gear 441 and the second sub-gear442 are engaged with each other. The assembly of the second rotarystructure 422 and the second fixed structure 412 is described above inconnection with FIG. 15.

Referring to FIG. 18, the second fixed structure 412 may have the secondinsertion hole 4172 into which the second connecting shaft 432 isinserted. A portion of the second connecting shaft 432 on which thesecond gear 4342 is formed may not be inserted into the second fixedstructure 412.

Referring to FIG. 19, the first fixed structure 411 and the second fixedstructure 412 may include the first coupling protrusion 4111 and thesecond coupling protrusion 4121, respectively. The first fixed structure411 and the second fixed structure 412 may be coupled together such thatthe first coupling protrusion 4111 is inserted into the depression ofthe second fixed structure 412 and the second coupling protrusion 4121is inserted into the depression of the first fixed structure 411.

Referring to FIG. 19, the first fixed structure 411 and the second fixedstructure 412 may be arranged such that the first rotary structure 421and the second rotary structure 422, which are coupled to the firstfixed structure 411 and the second fixed structure 412, respectively,rotate in opposite directions. For example, the spaces into which thefirst rotary structure 421 and the second rotary structure 422 areinserted may be open in opposite directions (e.g., the fourth directionand the third direction of FIG. 8). That is, the coupling directions inwhich the first rotary structure 421 and the second rotary structure 422are coupled to the fixed structures 411 and 412 may be opposite to eachother, and the rotational directions of the first rotary structure 421and the second rotary structure 422 may be opposite to each other.

FIG. 20 is a view illustrating welding of the first fixed structure andthe second fixed structure of the hinge module according to anotherembodiment.

Referring to FIG. 20, the first fixed structure 411 and the second fixedstructure 412 may be coupled together by another method. For example,the first fixed structure 411 and the second fixed structure 412 may becoupled by welding W. The welding may be done by electric welding, gaswelding, laser welding, and the like. In another example, the firstfixed structure 411 and the second fixed structure 412 may be coupled byscrews, bolts, rivets, etc.

FIG. 21 is a view illustrating assembly of the hinge housing and thefixed structure of the hinge module according to an embodiment.

Referring to FIG. 21, the hinge structure 41 may include fastening holes416 for fixing the fixed structure 41 to the hinge housing 25. The hingehousing 25 may include rods 231 protruding from the inside of the hingehousing 25. The hinge module 40 may be fixed to the hinge housing 25 bymounting the guide portions 411 c and 412 c of the fixed structure 41,which have the fastening holes 416 formed therein, onto the rods 231formed on the inside of the hinge housing 25. However, the couplingstructure of the hinge housing 25 and the fixed structure 41 disclosedherein is not limited to the method illustrated in the drawing is onlyan example.

The hinge module 40 according to the embodiment disclosed herein mayinclude the fixed structure 41 that includes the guide portion 41 c andthe central portion 41 a that guide opposite end portions of the rotarystructure 42 in the direction of the virtual axis of rotation H1 or H2,thereby fixing the displacement of the rotary structure 42 in thedirection of the virtual axis of rotation H1 or H2.

FIG. 22 is a view illustrating an invariance of the displacement of therotary structure when an external force is axially applied to the hingemodule according to an embodiment.

Referring to FIG. 22, the fixed structure 41 may include the first fixedstructure 411 and the second fixed structure 412 that is coupled to thefirst fixed structure 411. The first fixed structure 411 and the secondfixed structure 412 may be coupled together by welding to form one fixedstructure, or may be coupled together by insertion-coupling so as to beremovable, as described above.

In the illustrated embodiment, the first fixed structure 411 may includethe first central portion 411 a, the first support portion 411 b, andthe first guide portion 411 c. At least part of the first rotarystructure 421 may be surrounded by the first central portion 411 a, thefirst support portion 411 b, and the first guide portion 411 c. Thefirst rotary structure 421 may be disposed between the first centralportion 411 a and the first guide portion 411 c.

In the illustrated embodiment, the second fixed structure 412 mayinclude the second central portion 412 a, the second support portion 412b, and the second guide portion 412 c. At least part of the secondrotary structure 422 may be surrounded by the second central portion 412a, the second support portion 412 b, and the second guide portion 412 c.The second rotary structure 422 may be disposed between the secondcentral portion 412 a and the second guide portion 412 c.

In an embodiment, when an external force F is axially applied to thehinge module 40, the axial displacement of the first rotary structure421 or the second rotary structure 422 may be constrained by the guideportion 411 c or 412 c located on one side of the first fixed structure411 and the second fixed structure 412 and the central portion 411 a or412 a located on the opposite side thereof.

For example, some hinge modules may include a separate elastic member toapply an axial constraint force to the rotary structure. In contrast,the hinge module 40 according to the embodiment disclosed herein may fixthe axial displacement of the rotary structures 421 and 422 even thoughthe hinge module 40 does not additionally include the separate elasticcomponent. Accordingly, the hinge module 40 is able to be stably driven,and thus the reliability of the product may be improved. In addition,the number of components included in the hinge module 40 may be reduced,which makes it possible to simplify the assembly process and reduce thefailure rate.

FIGS. 23A and 23B are perspective views of a hinge module according toan embodiment. FIG. 24 is a plan view of the hinge module according toan embodiment. FIGS. 25A and 25B are views illustrating a rotationalmotion of the hinge module according to an embodiment.

Hereinafter, the hinge module described above with reference to FIGS. 6to 22 is referred to as the first hinge module 40, and the hinge modulethat will be described below is referred to as the second hinge module50.

Referring to FIGS. 23A and 23B, the second hinge module 50 may include afixed structure 51, and a first rotary structure 521 and a second rotarystructure 522 that are coupled to the fixed structure 51 so as to berotatable.

In the illustrated embodiment, the fixed structure 51 may include afirst sidewall 511, a second sidewall 512, a third sidewall 513, and afourth sidewall 514 that face the axis for which the first rotarystructure 521 and the second rotary structure 522 rotate. The directionof the axis is referred to here as an axial direction. The thirdsidewall 513 and the fourth sidewall 514 may be disposed between thefirst sidewall 511 and the second sidewall 512. A first space 5191 maybe formed between the first sidewall 511 and the second sidewall 512.The third sidewall 513 and the fourth sidewall 514 may be disposed inthe first space 5191. A second space 5192 may be formed between thethird sidewall 513 and the fourth sidewall 514. A third space 5193 maybe formed between the first sidewall 511 and the third sidewall 513 andbetween the second sidewall 512 and the fourth sidewall 514.

In the illustrated embodiment, the first rotary structure 521 mayinclude a body 521 a, and a first extension 521 b and a second extension521 c that extend from one side of the body 521 a. The first extension521 b and the second extension 521 c may extend from the body 521 a in adirection perpendicular to the axial direction. The first extension 521b and the second extension 521 c may be disposed in the third spaces5193. The body 521 a of the first rotary structure 521 may be disposedin the first space 5191. The second rotary structure 522 may be disposedin the second space 5192.

In the illustrated embodiment, the first sidewall 511 and the secondsidewall 512 may include first guide structures 5151 that protrudetoward the first extension 521 b and the second extension 521 c,respectively. The first extension 521 b and the second extension 521 cmay include first guide rails 5251 in which the first guide structures5151 are at least partially received, respectively.

In the illustrated embodiment, each of the third sidewall 513 and thefourth sidewall 514 may include a second guide structure 5152 protrudingtoward the second rotary structure 522. The second rotary structure 522may include a second guide rail 5252 in which at least part of thesecond guide structure 5152 is received.

In an embodiment, when in the flat state (FIG. 23A), at least part ofthe second rotary structure 522 may be disposed between the firstextension 521 b and the second extension 521 c of the first rotarystructure 521.

Referring to FIGS. 25A and 25B, the first rotary structure 521 and thesecond rotary structure 522 may rotate about a first virtual axis ofrotation and a second virtual axis of rotation, respectively. The firstguide rails 5251 of the first rotary structure 521 may be in a circulararc shape. The first guide structures 5151 may be in a circular arcshape so as to be received in the first guide rails 5251. The secondguide rails 5252 of the second rotary structure 522 may be in a circulararc shape. The second guide structures 5152 may be in a circular arcshape so as to be received in the second guide rails 5252.

Unlike the first hinge module 40 described above with reference to FIGS.6 to 21, the second hinge module 50 illustrated in FIGS. 23A to 25B doesnot include a gear structure (e.g., the connecting shaft 43 and thesub-gears 44 of FIG. 11) that links the first rotary structure 521 andthe second rotary structure 522, and therefore the first rotarystructure 521 and the second rotary structure 522 may be independentlydriven. Accordingly, the second hinge module 50 may be smoothly drivenwithout noise or vibration caused by gear engagement. However, the hingeassembly (e.g., the hinge assembly 4 of FIG. 3) of the electronic devicemay include the second hinge module 50 and at least one first hingemodule 40. Accordingly, the first rotary structure 521 and the secondrotary structure 522 of the second hinge module 50 may be linked witheach other by the first hinge module 40.

A hinge module 40 according to an embodiment of the disclosure mayinclude a first fixed structure 411 that includes a first centralportion 411 a, a first support portion 411 b extending from the firstcentral portion 411 a in a first direction, and a first guide portion411 c extending from the first support portion 411 b in a thirddirection perpendicular to the first direction, a second fixed structure412 that includes a second central portion 412 a coupled to one side ofthe first central portion 411 a that faces a second direction oppositeto the first direction, a second support portion 412 b extending fromthe second central portion 412 a in the second direction, and a secondguide portion 412 c extending from the second support portion 412 b in afourth direction perpendicular to the second direction, the second fixedstructure being integrally or removably coupled to the first fixedstructure, a first connecting shaft 431 that includes a first gear 4341formed on at least a part of an outer circumferential surface thereofand extends in the first direction and that passes through at least apart of the first central portion 411 a of the first fixed structure 411such that at least a part of the first gear 4341 is disposed between thefirst central portion and the first guide portion 411 c, a first rotarystructure 421 that is disposed between the first guide portion 411 c andthe first central portion 411 a and that includes a first circular arcshaped gear 4241 engaged with the first gear 4341, the first rotarystructure being coupled with the first connecting shaft 431 so as to berotated about a first virtual axis of rotation H1 passing through acenter of a circular arc of the first circular arc shaped gear 4241, asecond connecting shaft 432 that includes a second gear 4342 formed onat least a part of an outer circumferential surface thereof and extendsin the second direction and that passes through at least a part of thesecond central portion 412 a of the second fixed structure 412 such thatat least a part of the second gear 4342 is disposed between the secondcentral portion 412 a and the second guide portion 411 c, the firstconnecting shaft 431 and the second connecting shaft 432 being linkedwith each other so as to be rotated in opposite directions, and a secondrotary structure 422 that is disposed between the second guide portion411 c and the second central portion 412 a that includes a secondcircular arc shaped gear 4242 engaged with the second gear 4342, thesecond rotary structure being configured to be rotated about a secondvirtual axis of rotation H2 passing through a center of a circular arcof the second circular arc shaped gear 4242, by rotation of the secondconnecting shaft 432.

In an embodiment, the first rotary structure may have a first openingformed therein in a first circular arc shape, the first circular arcshaped gear may be a first internal gear formed on an inner wall of thefirst opening and engaged with the first gear of the first connectingshaft, the second rotary structure may have a second opening formedtherein in a second circular arc shape, and the second circular arcshaped gear may be a second internal gear formed on an inner wall of thesecond opening and engaged with the second gear of the second connectingshaft.

In an embodiment, the hinge module may further include an even number ofsub-gears 441 and 442 that are disposed between the first centralportion and the second central portion and that link the firstconnecting shaft 431 and the second connecting shaft 432.

In an embodiment, the first central portion 411 a and the second centralportion 412 a may include first guide structures 4141 protruding towardthe first rotary structure 421 and the second rotary structure 422,respectively, and the first guide portion 411 c and the second guideportion 412 c may include second guide structures 4142 protruding towardthe first rotary structure 421 and the second rotary structure 422,respectively. The first rotary structure 421 may include first guiderails 4231 formed on opposite surfaces of the first rotary structure andconfigured to receive at least a part of the first guide structure 4141,and the second rotary structure may include second guide rails 4232formed on opposite surfaces of the second rotary structure andconfigured to receive at least a part of the second guide structure4142.

In an embodiment, each of the first guide rails 4231 may include a firstcurved surface 423 a having a first radius of curvature with respect tothe first virtual axis of rotation H1 and a second curved surface 423 bhaving a second radius of curvature smaller than the first radius ofcurvature with respect to the first virtual axis of rotation H1, and thefirst guide structure 4141 may be disposed between the first curvedsurface 423 a and the second curved surface 423 b. Each of the secondguide rails 4232 may include a third curved surface 423 a having thefirst radius of curvature with respect to the second virtual axis ofrotation H2 and a fourth curved surface 423 b having the second radiusof curvature with respect to the second virtual axis of rotation H2, andthe second guide structure 4142 may be disposed between the third curvedsurface 423 a and the fourth curved surface 423 b.

In an embodiment, the first guide structure 4141 may include a firstcorresponding curved surface 414 a that makes contact with the firstcurved surface 423 a of the first guide rail 4231 and a secondcorresponding curved surface 414 b that makes contact with the secondcurved surface 423 b of the first guide rail 4231, a central angle of acircular arc of the second corresponding curved surface 414 b may besmaller than a central angle of a circular arc of the second curvedsurface 423 b, the second guide structure 4142 may include a thirdcorresponding curved surface 414 a that makes contact with the thirdcurved surface 423 a of the second guide rail 4232 and a fourthcorresponding curved surface 414 b that makes contact with the fourthcurved surface 423 b of the second guide rail 4232, and a central angleof a circular arc of the fourth corresponding curved surface 414 b maybe smaller than a central angle of a circular arc of the fourth curvedsurface 423 b.

In an embodiment, the first rotary structure 421 may include a firstcurved surface 4272 having a first radius of curvature with respect tothe first virtual axis of rotation H1, the first support portion 411 bmay include a first corresponding curved surface 4143 that supports thefirst curved surface 4272 to support the rotation of the first rotarystructure 421, the second rotary structure 422 may include a secondcurved surface 4274 having a second radius of curvature with respect tothe second virtual axis of rotation H2, and the second support portion412 b may include a second corresponding curved surface 4143 thatsupports the second curved surface 4274 to support the rotation of thesecond rotary structure 422.

In an embodiment, the first circular arc shaped gear 4241 may be betweenthe first connecting shaft 431 and the first virtual axis of rotation H1in a radial direction from the first virtual axis of rotation H1, andthe second circular arc shaped gear 4242 may be between the secondconnecting shaft 432 and the second virtual axis of rotation H2 in aradial direction from the second virtual axis of rotation H2.

A hinge module according to an embodiment of the disclosure may includea fixed structure 411 that includes a central portion 411 a, a guideportion 411 c having an edge facing an edge of the central portion 411a, and a support portion 411 b that connects the central portion 411 aand the guide portion 411 c, an interior space being formed between thecentral portion 411 a and the guide portion 411 c, a connecting shaft431 that extends into the interior space through the central portion 411a and that includes a gear 4341 formed on at least a part of an outercircumferential surface of the connecting shaft, and a rotary structure421 that is disposed in the interior space and that includes a circulararc shaped gear 4241 that includes a plurality of gear teeth arranged ina circular arc shape and that are engaged with the gear 4341, in whichthe rotary structure 421 rotates about a virtual axis of rotation H1passing through a center of a circular arc of the circular arc shapedgear 4241.

In an embodiment, the central portion 411 a may face a direction of thevirtual axis of rotation H1, and the support portion 411 b may face adirection perpendicular to the direction of the virtual axis of rotationH1.

In an embodiment, the rotary structure 421 may have a circular arcshaped opening 426 formed therein through which at least a part of theconnecting shaft 431 passes, and the circular arc shaped gear 4241 maybe an internal gear 4241 formed on an inner wall of the opening 426 andengaged with the gear 4341 of the connecting shaft 431.

In an embodiment, the internal gear 4241 may be between the connectingshaft 431 and the virtual axis of rotation H1.

In an embodiment, the central portion 411 a and the guide portion 411 cmay include guide structures 414 protruding toward the interior space,respectively, and the rotary structure 421 may include guide rails 4231and 4232 configured to receive the guide structures 414.

In an embodiment, the guide rails 4231 and 4232 may include first curvedsurfaces 423 a spaced apart from the virtual axis of rotation H1 by afirst distance in a radial direction and second curved surfaces 423 bspaced apart from the virtual axis of rotation H1 by a second distancein the radial direction, and the guide structures 414 may be receivedbetween the first curved surfaces 423 a and the second curved surfaces423 b of the guide rails.

In an embodiment, the guide structures 414 may include firstcorresponding curved surfaces 414 a that make contact with the firstcurved surfaces 423 a of the guide rails 4231 and 4232 and secondcorresponding curved surfaces 414 b that make contact with the secondcurved surfaces 423 b of the guide rails 4231 and 4232, and centralangles of circular arcs of the second corresponding curved surfaces 414b may be smaller than central angles of circular arcs of the secondcurved surfaces 423 b.

In an embodiment, the support portion 411 b may include a curved surfaceformed to support the rotation of the rotary structure 421.

An electronic device according to an embodiment of the disclosure mayinclude a housing structure including a first housing 21, a secondhousing 22, and a hinge housing 25 disposed between the first housing 21and the second housing 22, a flexible display 30 that is disposed on thehousing structure so as to extend from the first housing 21 to thesecond housing 22 and that includes a first area formed of a flatsurface of the first housing, a second area formed of a flat surface ofthe second housing, and a folding area formed between the first area andthe second area and configured to be folded to be flat or curved, and ahinge module 40 disposed in the hinge housing 25 and configured torotate the first housing 21 about a first virtual axis of rotation H1extending in a first direction and rotate the second housing 22 about asecond virtual axis of rotation H2 parallel to the first virtual axis ofrotation H1. The hinge module may include a fixed structure 41 fixedlydisposed in the hinge housing 25, the fixed structure including acentral portion 411 a, 412 a, a first support portion 411 b extendingfrom the central portion 411 a, 412 a in the first direction, a firstguide portion 411 c extending from the first support portion 411 b in athird direction perpendicular to the first direction, a second supportportion 412 b extending from the central portion 411 a, 412 a in asecond direction opposite to the first direction, and a second guideportion 412 c extending from the second support portion 412 b in afourth direction perpendicular to the second direction, a first rotarystructure 421 disposed between the first guide portion 411 c and thecentral portion 411 a, 412 a and connected with the first housing 21,and a second rotary structure 422 disposed between the second guideportion 412 c and the central portion 411 a, 412 a and connected withthe second housing 22.

In an embodiment, the first rotary structure 421 may be configured torotate about the first virtual axis of rotation H1 in a first rotationaldirection, and the second rotary structure 422 may be configured torotate about the second virtual axis of rotation H2 in a secondrotational direction opposite the first rotational direction.

In an embodiment, the hinge module 40 may further include a firstconnecting shaft 431 that extends from the central portion 411 a, 412 ain the first direction and includes a first gear 4341 and that passesthrough at least a part of the central portion 411 a, 412 a such that atleast a part of the first gear 4341 is disposed between the first guideportion 411 c and the central portion 411 a, 412 a and a secondconnecting shaft 432 that extends from the central portion 411 a, 412 ain the second direction and includes a second gear 4342 and that passesthrough at least a part of the central portion 411 a, 412 a such that atleast a part of the second gear 4342 is disposed between the secondguide portion 412 c and the central portion 411 a, 412 a. The centralportion 411 a, 412 a may include an even number of sub-gears 441 and 442that connect the first gear 4341 and the second gear 4342 to rotate thefirst connecting shaft 431 and the second connecting shaft 432 inopposite directions. The first rotary structure 421 may include a firstopening 4261 having a first circular arc shape whose center coincideswith the first virtual axis of rotation H1 and a first internal gear4241 formed in the first opening 4261 and engaged with the first gear4341, and the second rotary structure 422 may include a second opening4262 having a second circular arc shape whose center coincides with thesecond virtual axis of rotation H2 and a second internal gear 4242formed in the second opening 4262 and engaged with the second gear 4342.

In an embodiment, the first guide portion 411 c and the central portion411 a, 412 a may include first guide structures 4141 protruding towardthe first rotary structure 421, respectively, and the first rotarystructure 411 may include first guide rails 4231 formed on oppositesurfaces of the first rotary structure and configured to receive atleast a part of the first guide structures 4141. The second guideportion 412 c and the central portion 411 a, 412 a may include secondguide structures 4142 protruding toward the second rotary structure 422,respectively, and the second rotary structure 422 may include secondguide rails 4232 formed on opposite surfaces of the second rotarystructure and configured to receive at least a part of the second guidestructures 4142 are received.

The hinge module and the electronic device including the same accordingto the certain embodiments of the disclosure include a relatively smallnumber of components, thereby achieving a simple assembly process and areduction in failure rate.

In addition, according to the certain embodiments of the disclosure, therotation of the rotary structure may be constrained without a separateelastic member even when an external impact (e.g., from a drop) isapplied.

In addition, the disclosure may provide various other effects andadvantages that are directly or indirectly recognized.

While the disclosure has been shown and described with reference tovarious embodiments thereof, it will be understood by those skilled inthe art that various changes in form and details may be made thereinwithout departing from the spirit and scope of the disclosure as definedby the appended claims and their equivalents.

The electronic device according to various embodiments may be one ofvarious types of electronic devices. The electronic devices may include,for example, a portable communication device (e.g., a smartphone), acomputer device, a portable multimedia device, a portable medicaldevice, a camera, a wearable device, or a home appliance. According toan embodiment of the disclosure, the electronic devices are not limitedto those described above.

It should be appreciated that various embodiments of the presentdisclosure and the terms used therein are not intended to limit thetechnological features set forth herein to particular embodiments andinclude various changes, equivalents, or replacements for acorresponding embodiment. With regard to the description of thedrawings, similar reference numerals may be used to refer to similar orrelated elements. It is to be understood that a singular form of a nouncorresponding to an item may include one or more of the things, unlessthe relevant context clearly indicates otherwise. As used herein, eachof such phrases as “A or B,” “at least one of A and B,” “at least one ofA or B,” “A, B, or C,” “at least one of A, B, and C,” and “at least oneof A, B, or C,” may include any one of, or all possible combinations ofthe items enumerated together in a corresponding one of the phrases. Asused herein, such terms as “1st” and “2nd,” or “first” and “second” maybe used to simply distinguish a corresponding component from another,and does not limit the components in other aspect (e.g., importance ororder). It is to be understood that if an element (e.g., a firstelement) is referred to, with or without the term “operatively” or“communicatively”, as “coupled with,” “coupled to,” “connected with,” or“connected to” another element (e.g., a second element), it means thatthe element may be coupled with the other element directly (e.g.,wiredly), wirelessly, or via a third element.

According to various embodiments, each component (e.g., a module or aprogram) of the above-described components may include a single entityor multiple entities. According to various embodiments, one or more ofthe above-described components may be omitted, or one or more othercomponents may be added. Alternatively or additionally, a plurality ofcomponents (e.g., modules or programs) may be integrated into a singlecomponent. In such a case, according to various embodiments, theintegrated component may still perform one or more functions of each ofthe plurality of components in the same or similar manner as they areperformed by a corresponding one of the plurality of components beforethe integration. According to various embodiments, operations performedby the module, the program, or another component may be carried outsequentially, in parallel, repeatedly, or heuristically, or one or moreof the operations may be executed in a different order or omitted, orone or more other operations may be added.

What is claimed is:
 1. A hinge module comprising: a first fixedstructure including a first central portion, a first support portionextending from the first central portion in a first direction, and afirst guide portion extending from the first support portion in a thirddirection perpendicular to the first direction; a second fixed structureincluding a second central portion coupled to one side of the firstcentral portion that faces a second direction opposite to the firstdirection, a second support portion extending from the second centralportion in the second direction, and a second guide portion extendingfrom the second support portion in a fourth direction perpendicular tothe second direction, the second fixed structure being integrally orremovably coupled to the first fixed structure; a first connecting shaftincluding a first gear formed on at least a part of an outercircumferential surface thereof, the first connecting shaft extending inthe first direction, wherein the first connecting shaft passes throughat least a part of the first central portion of the first fixedstructure such that at least a part of the first gear is disposedbetween the first central portion and the first guide portion; a firstrotary structure disposed between the first guide portion and the firstcentral portion, the first rotary structure including a first circulararc shaped gear engaged with the first gear, wherein the first rotarystructure is coupled with the first connecting shaft so as to be rotatedabout a first virtual axis of rotation passing through a center of acircular arc of the first circular arc shaped gear; a second connectingshaft including a second gear formed on at least a part of an outercircumferential surface thereof, the second connecting shaft extendingin the second direction, wherein the second connecting shaft passesthrough at least a part of the second central portion of the secondfixed structure such that at least a part of the second gear is disposedbetween the second central portion and the second guide portion, and thefirst connecting shaft and the second connecting shaft are linked witheach other so as to be rotated in opposite directions; and a secondrotary structure disposed between the second guide portion and thesecond central portion, the second rotary structure including a secondcircular arc shaped gear engaged with the second gear, wherein thesecond rotary structure is configured to be rotated about a secondvirtual axis of rotation passing through a center of a circular arc ofthe second circular arc shaped gear, by rotation of the secondconnecting shaft.
 2. The hinge module of claim 1, wherein the firstrotary structure has a first opening formed therein in a first circulararc shape, wherein the first circular arc shaped gear is a firstinternal gear formed on an inner wall of the first opening and engagedwith the first gear of the first connecting shaft, wherein the secondrotary structure has a second opening formed therein in a secondcircular arc shape, and wherein the second circular arc shaped gear is asecond internal gear formed on an inner wall of the second opening andengaged with the second gear of the second connecting shaft.
 3. Thehinge module of claim 1, further comprising: an even number of sub-gearsdisposed between the first central portion and the second centralportion and configured to link the first connecting shaft and the secondconnecting shaft.
 4. The hinge module of claim 1, wherein the firstcentral portion and the second central portion include first guidestructures protruding toward the first rotary structure and the secondrotary structure, respectively, wherein the first guide portion and thesecond guide portion include second guide structures protruding towardthe first rotary structure and the second rotary structure,respectively, wherein the first rotary structure includes first guiderails formed on opposite surfaces of the first rotary structure andconfigured to receive at least a part of the first guide structures, andwherein the second rotary structure includes second guide rails formedon opposite surfaces of the second rotary structure and configured toreceive at least a part of the second guide structure.
 5. The hingemodule of claim 4, wherein each of the first guide rails includes afirst curved surface having a first radius of curvature with respect tothe first virtual axis of rotation and a second curved surface having asecond radius of curvature smaller than the first radius of curvaturewith respect to the first virtual axis of rotation, wherein the firstguide structure is disposed between the first curved surface and thesecond curved surface, wherein each of the second guide rails includes athird curved surface having the first radius of curvature with respectto the second virtual axis of rotation and a fourth curved surfacehaving the second radius of curvature with respect to the second virtualaxis of rotation, and wherein the second guide structure is disposedbetween the third curved surface and the fourth curved surface.
 6. Thehinge module of claim 5, wherein the first guide structure includes afirst corresponding curved surface configured to make contact with thefirst curved surface of the first guide rail and a second correspondingcurved surface configured to make contact with the second curved surfaceof the first guide rail, wherein a central angle of a circular arc ofthe second corresponding curved surface is smaller than a central angleof a circular arc of the second curved surface, wherein the second guidestructure includes a third corresponding curved surface configured tomake contact with the third curved surface of the second guide rail anda fourth corresponding curved surface configured to make contact withthe fourth curved surface of the second guide rail, and wherein acentral angle of a circular arc of the fourth corresponding curvedsurface is smaller than a central angle of a circular arc of the fourthcurved surface.
 7. The hinge module of claim 1, wherein the first rotarystructure includes a first curved surface having a first radius ofcurvature with respect to the first virtual axis of rotation, whereinthe first support portion includes a first corresponding curved surfaceconfigured to support the first curved surface to support rotation ofthe first rotary structure, wherein the second rotary structure includesa second curved surface having a second radius of curvature with respectto the second virtual axis of rotation, and wherein the second supportportion includes a second corresponding curved surface configured tosupport the second curved surface to support rotation of the secondrotary structure.
 8. The hinge module of claim 1, wherein the firstcircular arc shaped gear is between the first connecting shaft and thefirst virtual axis of rotation in a radial direction from the firstvirtual axis of rotation, and wherein the second circular arc shapedgear is between the second connecting shaft and the second virtual axisof rotation in a radial direction from the second virtual axis ofrotation.
 9. A hinge module comprising: a fixed structure including acentral portion, a guide portion having an edge facing an edge of thecentral portion, and a support portion configured to connect the centralportion and the guide portion, wherein an interior space is formedbetween the central portion and the guide portion; a connecting shaftextending into the interior space through the central portion andincluding a gear formed on at least a part of an outer circumferentialsurface of the connecting shaft; and a rotary structure disposed in theinterior space, the rotary structure including a circular arc shapedgear having a plurality of gear teeth arranged in a circular arc shapeand that are engaged with the gear, wherein the rotary structure rotatesabout a virtual axis of rotation passing through a center of a circulararc of the circular arc shaped gear.
 10. The hinge module of claim 9,wherein the central portion faces a direction of the virtual axis ofrotation, and wherein the support portion faces a directionperpendicular to the direction of the virtual axis of rotation.
 11. Thehinge module of claim 9, wherein the rotary structure has a circular arcshaped opening formed therein through which at least a part of theconnecting shaft passes, and wherein the circular arc shaped gear is aninternal gear formed on an inner wall of the opening and engaged withthe gear of the connecting shaft.
 12. The hinge module of claim 11,wherein the internal gear is between the connecting shaft and thevirtual axis of rotation.
 13. The hinge module of claim 9, wherein thecentral portion and the guide portion include guide structuresprotruding toward the interior space, respectively, and wherein therotary structure includes guide rails configured to receive the guidestructures.
 14. The hinge module of claim 13, wherein the guide railsinclude first curved surfaces spaced apart from the virtual axis ofrotation by a first distance in a radial direction and second curvedsurfaces spaced apart from the virtual axis of rotation by a seconddistance in the radial direction, and wherein the guide structures arereceived between the first curved surfaces and the second curvedsurfaces of the guide rails.
 15. The hinge module of claim 14, whereinthe guide structures include first corresponding curved surfacesconfigured to make contact with the first curved surfaces of the guiderails and second corresponding curved surfaces configured to makecontact with the second curved surfaces of the guide rails, and whereincentral angles of circular arcs of the second corresponding curvedsurfaces are smaller than central angles of circular arcs of the secondcurved surfaces.
 16. The hinge module of claim 9, wherein the supportportion includes a curved surface formed to support rotation of therotary structure.
 17. An electronic device comprising: a housingstructure including a first housing, a second housing, and a hingehousing disposed between the first housing and the second housing; aflexible display disposed on the housing structure so as to extend fromthe first housing to the second housing, the flexible display includinga first area formed of a flat surface of the first housing, a secondarea formed of a flat surface of the second housing, and a folding areaformed between the first area and the second area and configured to befolded to be flat or curved; and a hinge module disposed in the hingehousing and configured to rotate the first housing about a first virtualaxis of rotation extending in a first direction and rotate the secondhousing about a second virtual axis of rotation parallel to the firstvirtual axis of rotation, wherein the hinge module includes: a fixedstructure fixedly disposed in the hinge housing, the fixed structureincluding a central portion, a first support portion extending from thecentral portion in the first direction, a first guide portion extendingfrom the first support portion in a third direction perpendicular to thefirst direction, a second support portion extending from the centralportion in a second direction opposite to the first direction, and asecond guide portion extending from the second support portion in afourth direction perpendicular to the second direction; a first rotarystructure disposed between the first guide portion and the centralportion and connected with the first housing; and a second rotarystructure disposed between the second guide portion and the centralportion and connected with the second housing.
 18. The electronic deviceof claim 17, wherein the first rotary structure is configured to rotateabout the first virtual axis of rotation in a first rotationaldirection, and the second rotary structure is configured to rotate aboutthe second virtual axis of rotation in a second rotational directionopposite the first rotational direction.
 19. The electronic device ofclaim 18, wherein the hinge module further includes: a first connectingshaft extending from the central portion in the first direction andincluding a first gear, the first connecting shaft being configured topass through at least a part of the central portion such that at least apart of the first gear is disposed between the first guide portion andthe central portion; and a second connecting shaft extending from thecentral portion in the second direction and including a second gear, thesecond connecting shaft being configured to pass through at least a partof the central portion such that at least a part of the second gear isdisposed between the second guide portion and the central portion,wherein the central portion includes an even number of sub-gearsconfigured to connect the first gear and the second gear to rotate thefirst connecting shaft and the second connecting shaft in oppositedirections, wherein the first rotary structure includes a first openinghaving a first circular arc shape whose center coincides with the firstvirtual axis of rotation and a first internal gear formed in the firstopening and engaged with the first gear, and wherein the second rotarystructure includes a second opening having a second circular arc shapewhose center coincides with the second virtual axis of rotation and asecond internal gear formed in the second opening and engaged with thesecond gear.
 20. The electronic device of claim 17, wherein the firstguide portion and the central portion include first guide structuresprotruding toward the first rotary structure, respectively, wherein thefirst rotary structure includes first guide rails formed on oppositesurfaces of the first rotary structure and configured to receive atleast a part of the first guide structures, wherein the second guideportion and the central portion include second guide structuresprotruding toward the second rotary structure, respectively, and whereinthe second rotary structure includes second guide rails formed onopposite surfaces of the second rotary structure and configured toreceive at least a part of the second guide structures.